PEP Review 91-1-1
Isobutane Dehydrogenation by Thermal Cracking
Published: March 1992
A subsidiary of The Coastal Corporation, through Foster Wheeler, has reintroduced its Isobutane Cracking Process (CICP), which was first used in 1969 and shut down in the 1970s. CICP is a thermal cracking process that converts isobutane to isobutylene and propylene in the presence of steam using tubular furnaces. Pilot plant data show that the typical optimum conversion is in the range of 40% to 51% per pass. This process operates at a sufficiently high pressure so that the effluent without further compression can be fed directly to a vapor recovery unit.
Various processing options for the dehydrogenation product stream are possible. The product stream, after C5+ and/or C2 and lighter removal, can be sent directly to an MTBE unit or fractionated to produce high-purity propylene and an isobutylene-rich stream. The latter can serve as feedstock for MTBE or high-purity isobutylene manufacture. Alternatively, the dehydrogenation product stream can be used in other molecular-weight-increase operations such as alkylation and catalytic polymerization.
In this review, we evaluate the addition of a CICP unit for MTBE production integrated with an existing fluid catalytic cracking (FCC) refinery as well as the use of CICP in a stand- alone MTBE complex.